During intermediate vehicle stops such as at a traffic light, an engine may idle for some time. In order to increase fuel efficiency and improve emissions quality, the vehicle engine may be equipped with a start/stop function to reduce prolonged idling by temporarily shutting down the engine and then restarting the engine when restart conditions are met. The engine start/stop function may be carried out in the presence of a vehicle operator in order to ensure that the engine is not stopped without indication from the operator. By enabling the start/stop function in the presence of an operator, the engine may be restarted immediately responsive to an increase in engine torque request.
Various approaches are provided for initiating engine start/stop function based on the presence of a vehicle operator. In one example, as shown in U.S. Patent Application 2012/0138006, Gwon et al. teaches, determining a position of a driver door and in response to the driver door being open, even if other conditions for engine idle-stop being satisfied, not initiating an engine idle-stop.
However, the inventors herein have recognized potential issues with such systems. As one example, certain vehicles may be equipped with doors which may be dis-assembled from the vehicle body by an operator during certain driving situations such as off road driving etc. In the method shown by Gwon et al., the start/stop function may not be enabled during operation of the vehicle without the presence of the door. By not stopping the vehicle during prolonged periods of engine idling, fuel consumption may increase and emission quality may reduce. Also, if the engine is auto-stopped while the driver door is detached from the vehicle body, the driver may leave the vehicle without having to open the door. In response to a request for engine power from an auxiliary device such as an air conditioner, the engine may restart and the vehicle may be undesirably propelled in the absence of the driver.
In one example, the issues described above may be addressed by a method for a vehicle comprising: detecting whether a driver side vehicle door is attached or absent, selecting a start/stop strategy for an engine propelling the vehicle based on the driver side vehicle door attachment state, and further selecting the start/stop strategy based on a type of transmission coupled between the engine and the vehicle. In this way, by detecting each of a state of attachment of a door and a presence of the driver in the vehicle, engine start/stop function may be optimized for a vehicle with detachable driver door.
As an example, a vehicle may be equipped with a door control unit (DCU) located outside the driver door. In response to idle-stop conditions being met (such as in response to a longer than threshold duration of engine idling), the DCU may detect the presence of the driver door based on an input from a switch coupled to a door connector shunt. The DCU may further detect the presence of the door by sending a signal to a window motor used for operating the driver side window coupled to the door. If it is detected that the driver door has been detached, the controller may determine if a seat belt coupled to the driver's seat is in a buckled state. If the seat belt is fastened, it may be inferred that even if the driver door is not present, the driver is at his seat and an engine idle-stop may be initiated by suspending engine combustion. During an idle-stop, in response to engine restart conditions being met, combustion may be resumed after confirmation that the seat belt is still fastened. An engine start/stop strategy may be further adjusted based on a type of transmission system (automatic transmission or manual transmission) coupled to the vehicle.
In this way, by opportunistically using the engine start/stop function in vehicles with detachable doors, fuel efficiency and emissions quality may be maintained. By detecting a state of attachment of the driver door, the idle-stop procedure may be suitably modified for a situation where the driver door has been detached. The technical effect of detecting the presence of the driver by determining a state of the driver's seat belt is that an idle-stop or an engine restart may be scheduled upon confirmation that the operator is present in the vehicle. By modifying the start/stop strategy based on vehicle transmission system, engine efficiency may be improved, in this way, the overall fuel efficiency and drive experience of the operator during engine start/stop operations may be improved.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.